RE: Trainer that would eventually lead up to flying a Piper J-3 Cub
Either of those ARFs would work well in the 60 size variety. Also if you are a builder and can kit build a plane get a Carl Goldberg Piper Cub kit and build it with some dihedral in the wing and it becomes a very stable Piper Cub. I flew one with an OS 60 for a while and it got me used to tail draggers.